Dogs On Cancer's Scent
Can dogs' facility at sniffing out tumors be turned into a sensitive diagnostic tool?
Since 1989, when the Lancet published the first anecdote of a dog detecting cancer in its owner—in that case, constantly licking and even trying to bite off a mole that was later diagnosed as malignant melanoma—there have been numerous studies of canines sniffing out lung, prostate, colon, breast and ovarian cancers. Although the studies have been small, in some the dogs correctly identified cancer 100% of the time.
Training enough dogs to screen millions of people for cancer is hardly practical. Instead, the University of Pennsylvania School of Veterinary Medicine’s Working Dog Center wants to use dogs’ keen sense of smell—dogs have about 2.5 times as many functional olfactory receptor genes as humans—to isolate the specific volatile organic compounds that cancer produces. Those VOCs could then become the foundation of a test to screen for the compounds in breath or urine.
Three dogs will be trained to recognize the VOCs from tissue samples of ovarian cancer. As the dogs progress to identify cancer from blood samples, scientists at the University of Pennsylvania and the Monell Chemical Senses Center will use mass spectroscopy and nanotechnology analytic instruments to determine which compounds the dogs are detecting. “We’ll keep refining until we find the signature of early-stage ovarian cancer,” says veterinarian Cynthia Otto, director of the Working Dog Center. And even then, the dogs may have a role. “Once we have a screening test, I can see the dogs being called upon when results aren’t a clear positive or negative,” says Otto. “The dogs could be the final judge on whether cancer is present.”